The Vietnamese version of an open-faced omelet or crêpe, this specialty of many streetside restaurants is also called the "Happy Pancake." and probably doesn't refer to the well remembered pancakes of Phnom Penh  :) The Vietnamese name, khoai, comes from the type of pan it is cooked in. Banh xeo is the large southern version and is the basis of the Khmer Pancake referred to in this collection.
 
(240 ml)1 cup rice flour
(360 ml) 1-1/2 cups water
2 eggs, beaten
Small pinch of salt
(5 ml) 1 teaspoon superfine sugar
(60 ml) 1/4 cup mung beans (optional), soaked
   overnight, and steamed for 15 minutes
(120 ml) 1/2 cup finely sliced straw mushrooms
(100 Gm) 3-1/2 ounces of small shrimp, boiled and peeled
3 strips of thinly sliced cooked lean pork
   {or grill 3 rashers of bacon}.
(120 ml) 1/2 cup bean sprouts
(60 ml) 1/4 cup spring onions, chopped sprigs
   of fragrant herbs (basil, mint, **perilla
   and wild *betel leaves)
1/2 cup iceberg lettuce leaves
(30 ml) 2 tablespoons cooking oil
(240 ml) 1 cup Soy Sauce Dip

 ** Perilla is also known as purple mint, Japanese basil, or wild coleus and has a strong taste comparable to fennel or ordinary mint. I have no idea of its general availability in the west.

Blend rice flour with water, eggs, salt and sugar, leave to rest for 10 minutes, mix again then strain.

Add one tablespoon of oil to the frying pan, and swirl it around. Turn heat on high. Ladle the rice flour mix into the hot pan, swirl it around quickly, then add the mung beans and mushrooms. Cook covered for 1 minute.
Remove the lid. Add the shrimp, pork, bean sprouts and spring onions. Cook uncovered until the pancake is golden brown and crispy.

Serve with fragrant herbs, lettuce and Soy Sauce Dip.
Helpful hints: Timing is very important in cooking this dish. It should be prepared over a very high heat (to crisp the pancake). An 8-10 inch non-stick pan is ideal. The pancake should be wafer thin.